NASA announced today that the Curiosity research robot on Mars has discovered evidence of an ancient stream bed, where rocks have been worn smooth by deep, fast moving water. The photo above illustrates the similarities between Martian and terrestrial, alluvial soil.
My prediction (you read it here first) is that Curiosity will discover convincing evidence that life exists or has existed on the red planet.
Life depends on liquidity. In May of 2002, the Mars Odyssey probe found evidence of frozen water in deposits up to two feet thick around the southern Martian pole, amounting to trillions of gallons in all--more than double the volume of water in Lake Michigan. Presumably that water flowed at one time, and on earth even very cold environments can harbor biological activity. The McMurdo Dry Valleys of Antarctica, at first sight an arid wasteland looking very much like a rubbled Martian plain, contain at least twenty species of photosynthetic bacteria, a like number of algae, and a number of invertebrate animals such as mites, springtails, and other diminutive critters at the top of the food chain. All these "extremophiles" (creatures adapted to adverse conditions) depend on a brief summer flow of runoff from surrounding icefields for their sustenance. As for Mars? "Where there's water, there's life, one NASA scientists predicts.
Life is robust and probably widespread in our cosmos. When I was in high school (eons ago), we learned about an experiment at the University of Chicago where experimenters flashed an electric spark through a container filled with methane, ammonia, hydrogen and water (presumably mimicking the earth's primitive atmosphere) to produce amino acids, the building blocks of proteins and life. Stanley Miller and Harold Urey, the researchers, concluded that life might have begun when a stray flash of lightening struck a pond filled with "primordial soup." Yet now we know that amino acids are everywhere, found on meteorites and in the depths of interstellar space. Life on earth didn't have to wait around for lightening to strike. It almost certainly began as soon as the planet's crust had cooled sufficiently to allow water to precipitate from the atmosphere and gather in shallow seas. Thus the fossil record here on earth stretches back almost 4 billion years, nearly as old as the planet itself. There was no lengthy period of gestation needed for life to occur.
And what will the discovery that life exists on other planets mean for the human race? The old story of salvation--that our species is singular in the cosmos, created in the image of God--will be harder to sustain. But appreciation and admiration for the ingenious creativity of life itself, endlessly generative and prolific, can only be enhanced. For humanity, won't it be nice to know that we have company?